Google Nest · Thermostats
Google Nest Heat Link Installation in London
Updated
The Heat Link is the box near your boiler that a 3rd gen Nest Learning Thermostat uses to switch the heating and hot water. When it stops responding or sits too close to the boiler, a vetted JACK pro in London replaces it like for like or moves it, on its existing wiring and outside the boiler, for a fixed price in the JACK app before you book. If yours has failed, speak to Google first: some faulty 3rd gen Heat Links have been replaced at no cost.
In short
Yes, where the Heat Link is mounted outside the boiler. A vetted JACK pro in London swaps a failed 3rd gen Heat Link for a new one on the same wiring and the same relay or OpenTherm set-up, or moves it at least 30 cm from the boiler, as Google asks. Contact Google Nest support before booking, since Google has replaced some faulty 3rd gen Heat Links free. JACK sends wiring inside the boiler, and boiler faults, to a Gas Safe engineer.
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Nest Heat Link: key facts
- What it does
- Replaces your programmer and, with the thermostat, runs the heating and hot water; mounted near the heating system Source: Google Nest Help: Heat Link for Nest thermostats in Europe
- Telling Heat Links apart
- Three status lights on the 3rd gen Heat Link, two on the battery Heat Link E, one on the 2nd gen Source: Google Nest Help: Heat Link for Nest thermostats in Europe
- Power and switching
- Input 100–240 V AC, 50/60 Hz; two relays rated 3 (1) A at 230 V AC; 12 V DC out to the thermostat Source: Google Store UK: Nest Learning Thermostat (3rd gen) tech specs
- Terminals
- L and N; heating 1, 2, 3; hot water 4, 5, 6; OpenTherm OT1 and OT2; T1 and T2 to the thermostat, with earth connected whenever T1 and T2 are used Source: Google: 3rd gen Nest Learning Thermostat installation guide, UK and Ireland (PDF)
- Cable and class
- Conductors up to 2 mm²; Class I equipment with a functional earth terminal Source: Google: 3rd gen Nest Learning Thermostat installation guide, UK and Ireland (PDF)
- Distance from the boiler
- At least 30 cm from the boiler or other large metal objects Source: Google Home Help: troubleshooting Nest thermostat help codes
- Distance to the thermostat
- Within 30 m; Google warns that walls and large objects in between can cut the range Source: Google: 3rd gen Nest Learning Thermostat installation guide, UK and Ireland (PDF)
- Free replacements
- From 2022 Google replaced some faulty 3rd gen Heat Links in the UK at no cost, whatever their warranty status, with a professional supplying and fitting the new one Source: 9to5Google: Google replacing some 3rd gen Nest Heat Links (23 September 2022)
- Boiler-linked faults
- Google's UK help sends a new Heat Link needed because of a boiler problem to the installation company Google names for the UK Source: Google Nest Help: professional help setting up Nest products (UK section)
Device facts come from Google Nest Help (UK), the Google Store UK and Google's UK installation guide, linked beside each fact. Several Nest models are out of stock or no longer sold in the UK, so these pages are written for the device you already own: check its name on the box, in the app or on its base, and send it with your request. Last checked 1 November 2026.
How the Nest Heat Link is powered and mounted
A 3rd gen Heat Link takes mains in, sends two relay outputs to the boiler and the hot water, and feeds 12 V up to the display. Because it replaced the old programmer, it usually sits where that was, or at a junction box or wiring centre near the boiler. Swapping a failed one for a new one in the same place, on the same wires and with the same relay or OpenTherm set-up, is a replacement at the wall: it is not gas work, and it is not notifiable electrical work.
Before paying anyone, contact Google Nest support. In 2022 Google began replacing some faulty 3rd gen Heat Links in the UK free of charge, even out of warranty, through an installer Google arranged, and its UK help still points Heat Link replacements caused by a boiler problem to that installer. If Google will not cover yours, or you already have a replacement Heat Link, a JACK pro fits the one you supply.
Position causes trouble too. Google's help-codes page asks for the Heat Link to be at least 30 cm from the boiler or other large metal objects, and the UK guide keeps it within 30 m of the thermostat. Moving one off the boiler casing to a spot on the wall nearby, on the circuit it already uses, is wall-side work. If its cables run into the boiler's own terminals, JACK leaves that end to a Gas Safe engineer.
What the pro checks first
- Which Heat Link you have, from its status lights: three on a 3rd gen, two on a Heat Link E, one on a 2nd gen
- Whether Google Nest support has already offered a free replacement, so you do not pay twice
- Where its cables go: to a junction box or wiring centre, or into the boiler's own terminals
- Whether it runs the boiler by relay or by OpenTherm, so the new one is set up the same way
- How close it sits to the boiler and other large metal objects
What the pro does on the Nest Heat Link
- Heat Link's 230 V supply switched off at its spur and tested dead
- Every core labelled to its terminal before the old Heat Link comes off: L, N, earth, 1 to 6, OT1 and OT2, T1 and T2
- New Heat Link connected to the same terminals, or the existing one re-sited at least 30 cm from the boiler on its own circuit
- Thermostat paired again with the Heat Link and checked over Wi-Fi in the app
- Heating relay, and on cylinder systems the hot water relay, tested on and off
- For the 230 V work, ask your pro for a Minor Electrical Installation Works Certificate
How the Nest Heat Link installation goes
- 1Google Nest support contacted first, and their answer or case number shared with the pro
- 2Your photos of the Heat Link, its lights and its cables checked before the visit
- 3Power isolated, and the existing wiring photographed and labelled
- 4Replacement Heat Link fitted, or the existing one moved, on the same cables
- 5Thermostat paired to it and the boiler's response checked from the display
- 6Schedules and hot water checked in the app before the pro leaves
Before you book: what to send
- A photo of the Heat Link with its lights showing, and one of the cables going into it
- What Google Nest support told you, with any case number
- The boiler's make and model, and whether you have a hot water cylinder
- Any help code showing on the thermostat
- Whether you already have the replacement Heat Link
Which Heat Link jobs can a JACK pro do?
The wall side, on the wiring that is already there. Anything that means opening the boiler goes elsewhere.
| Heat Link job | Who does it | On a JACK booking |
|---|---|---|
| Like-for-like swap of a Heat Link mounted outside the boiler, same wiring and same mode | A competent pro: not gas work, not notifiable | Yes |
| Moving it at least 30 cm from the boiler, on its existing circuit | A competent pro who does electrical work | Yes |
| A Heat Link whose cables connect inside the boiler | A Gas Safe engineer for the boiler end (JACK's rule) | Wall side only |
| Changing from relay to OpenTherm control, or back | A Gas Safe engineer at the boiler (JACK's rule) | No |
| Finding or fixing a boiler fault behind a help code | A Gas Safe engineer | No |
| A new circuit from the consumer unit | A registered electrician | No |
Drawn from HSE code of practice L56, Gas Safe Register's guidance on home improvements and the Building Regulations 2010 for England, as read on 1 November 2026. Sending boiler-end wiring to a Gas Safe engineer is JACK's own rule, where the law is less clear-cut. This summary is not legal advice.
How is Google Nest installation priced in London?
A vetted pro prices your Nest job from the model and your photos, and the JACK app shows that fixed price before you book.
Full pricing guide for Google Nest installationFrequently asked questions
My Nest Heat Link has no lights. Does it need replacing?
Not necessarily. A 3rd gen Heat Link runs on mains power, so with no lights at all the pro first checks the fused spur and the supply reaching it. Only once the supply is proved good is the Heat Link itself treated as faulty, and at that point Google Nest support is worth contacting before anything is bought.
Is the Heat Link E replaced the same way?
No. The Heat Link E that pairs with the Nest Thermostat E sits where a room thermostat was and runs on a pair of AA lithium cells rather than mains, so flat batteries are the first thing to rule out. Google's app warns when they run low.
Does a Heat Link replacement need a Gas Safe engineer?
Not when the Heat Link is outside the boiler and the new one goes on the same wiring: the HSE treats replacing electric thermostats and timer switches as outside the gas regulations. JACK treats it as a job for a Gas Safe engineer when it means opening the boiler or wiring to its terminals, and when a boiler fault sits behind the Heat Link's error.
How much does Google Nest Heat Link installation cost in London?
It is a fixed price for your Nest Heat Link, worked out by a vetted pro from the model, a photo of where it is going and what power is there now, and shown in the JACK app before you book. Other devices can go on the same booking for one price. If you would rather pay for time, hourly hire for smart home is typically £45–£95 per hour as a guide.
Often booked together
Nest Learning Thermostat (3rd gen) installation
The UK and Ireland 3rd gen with its mains Heat Link: the Heat Link goes where your programmer was, the display on the wall or a stand.
Nest Thermostat E installation
The Heat Link E swapped in for your wired room thermostat on two of its wires, and the display set on its stand where it reads the room.
More Google Nest thermostats
Google Nest thermostat installation
The Nest Learning Thermostat (3rd gen) and the Nest Thermostat E, with their Heat Links fitted on the wiring you already have.
All Google Nest installation guides
Google Nest installation in London: thermostats and Heat Links, doorbells, Nest Cams and Nest Protect fitted by vetted pros. See a fixed price first.
Related services in London
Sources
The device facts and rules on this page come from these pages, checked on 1 November 2026.
- Google Nest Help: Heat Link for Nest thermostats in Europe
- Google: 3rd gen Nest Learning Thermostat installation guide, UK and Ireland (PDF)
- Google Home Help: troubleshooting Nest thermostat help codes
- 9to5Google: Google replacing some 3rd gen Nest Heat Links (23 September 2022)
- Gas Safe Register: home improvements
Jack All Trades (JACK) is an independent London service for booking vetted local pros. It is not part of, affiliated with or endorsed by Google LLC, and it is not part of Google's Nest Pro programme. Google Nest product names are used only to describe the devices JACK pros install; prices are set by JACK pros, not by Google, and JACK does not sell Nest devices. JACK pros do not open boilers or claim Gas Safe registration.
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